Quenching O1 Tool Steel

[snarble]

Hello everyone, another quick question about knife making?

Can you quench O1 in water? Seems like the cleaner approach. If yes is there anything I need to know about using water to quench?

If you need to use oil, will any oil work? which one works best?

Also... after tempering do you quench or allow the steel to cool slowly?

Thanks.

 

[sasquatch]

I wouldn't try water! Used motor oil is easy to get and works a treat. Quench for 3 seconds, remove for three then quench again for 3 seconds. Pop it in the oven at about 200 degrees for an hour, then turn off the oven and let it cool naturally...

 

[robin wood]

Yes you can use water though it is a harsher quench, that means because it boils at a low temperature lots of new cold water is drawn against the steel cooling it more quickly. If what you are quenching is small and thin this is fine and will get a bit more hardness. If what you are quenching is big it can set up stresses leading to bending or cracks.

anything over 5" blade or 3mm thick I would use oil, below that I use water.

After tempering it makes no difference if you quench or cool slowly.

 

[C_Claycomb]

Sure, you can quench in anything you like...

However, results may vary

As stated, water is a faster quench than oil and O-1 does not require a fast quench. You have about 10 seconds to get the blade from around 810dgC to below about 400degC. Things that need water are closer to 1 second (give or take).

Yes, oil is a bit messy but it isn't all that bad, I use old newspapers to get most of the oil off.

I used vegetable oil with good results. I did not remove the blade from the quench, with the slower hardening curve of O-1 it probably dosn't hurt on thin blades, but it would be just my luck if I tried that for the edge to get hard, then to take it out and the residual heat to start tempering before I got it back in the quench

Tempering times will differ for you depending on your gear. Many people favour three tempering cycles and some carry them out at different temperatures. Start with about 170degC (about 350F). On a forge hardened blade you probably won't achieve full hardness so you won't need such a high tempering temperature. Clean off a bit of the blade with sand paper before popping in the oven and you will see temper colours when you remove it. Look for a light straw yellow to start with. The test for temper is something called the "brass rod test" where you clamp up a bit of brass rod, sharpen your edge and polish it, then flex the very edge against the rod. If it chips, you know it needs more tempering, if it deforms and doesn't spring back, you over did it. Once you have experimented a bit you may not need to do this with every blade, but it can still be good practice.

My kitchen oven does not seem to hold temperature, if I leave a blade in there longer than an hour at a time, it seems to over temper it, they get too soft. If you have access to a digitally controlled furnace and can soak the O-1 at 810C for about 10 minutes, then you would need to up the tempering temperature, possibly high enough that you get blue colours on the steel. A friend of mine, using 52100 bearing steel, tempered to the blue range and still had over 60Rc because he had got his soak times right in his high temperature oven.

I would recommend that you go over to Bladeforums, Knifenetwork and Britishblades, and look up info on heat treating there. There are more experts there, and more discussions on what is a fairly specialist subject.

Very best of luck!!

 

[robin wood]

I would suggest just try it. O1 is very forgiving and really easy peasy to harden and temper.

1 heat to dull cherry and quench, if in doubt about if you have the right temp check with a magnet, it goes non magnetic at the temp you want, check quick though and quench immediately don't let it hang around and cool a bit then quench. Don't heat way past the non magnetic point (say bright orange heat) as then you start to get big crystals growing in the steel.

2 test the blade with a file, if it has hardened properly the file should skid off like off glass, if it bites the metal repeat step 1

3 polish a little of the blade and heat in a domestic oven to about 220 degress c which should give a nice deep staw colour. Don't trust your temp dial keep peeking at the colour and as soon as you see that straw colour pull it out and let it cool.

Simple as that. This process works well for spring steels too like en47 or old car springs.

 

[sasquatch]

Heh heh, I should have pointed out that's just the technique I use and it works for me. I've got the most basic set-up going and figured if you were asking about this on a bushcraft site you'd be doing it at a basic level as well. I use a bbq and hair dryer to heat the blade, check it's non magnetic with a big speaker magnet and quench in used motor oil...As mentioned blade sites have a wealth of info depending on what you want to do.

 

[FGYT]

new Veg oil for me from Lidles works well and you get a nice smell of chips i just put it in and leave for several mins or when ive finished the batch then into a bucket of cold water to cool and wash of with a bit of washing up liquid

best to use a metal tin ( i use a baby powder tin) and carful not to drop the knifes as the point could punch a hole in the bottom

ATB

Duncan

 

[HillBill]

3 polish a little of the blade and heat in a domestic oven to about 220 degress c which should give a nice deep staw colour.
.

If i may add a little to that?

Wrap your bade in foil ( shiney side out)

2mm should be in for around 45 minutes
3mm for an hour
4mm for 1 hour 10 minutes

These are what works in my oven and gives an even temper throughout the blade

 

[HillBill]

Heh heh, I should have pointed out that's just the technique I use and it works for me. I've got the most basic set-up going and figured if you were asking about this on a bushcraft site you'd be doing it at a basic level as well. I use a bbq and hair dryer to heat the blade, check it's non magnetic with a big speaker magnet and quench in used motor oil...As mentioned blade sites have a wealth of info depending on what you want to do.

That is all you need for 01. Once your used to it no amount of fancy ovens etc will make it noticably better.

 

[sasquatch]

That is all you need for 01. Once your used to it no amount of fancy ovens etc will make it noticably better.

Aye, it works for me! Keep it simple as far as I'm concerned. I'm not making blades to sell so as long as I'm happy with the abuse I can throw at them it's all good. As you said I wrap my blades in foil before popping them in the oven but I forgot to mention that bit...

Snarble- here's the tutorial I used to get started;

http://www.britishblades.com/forums/showthread.php?t=57990

Where abouts you from in Canada?

 

[robin wood]

If i may add a little to that?

Wrap your bade in foil ( shiney side out)

2mm should be in for around 45 minutes
3mm for an hour
4mm for 1 hour 10 minutes

These are what works in my oven and gives an even temper throughout the blade

Whatever works for you is good.

For folks just starting out I like to keep it as simple as poss because it is so easy to spend lots of time reading and getting confused because everyone does it different. Far better to just get out there and do a few and see how they work. It really is easy once you start trying it.

The worst that can happen is 1 you make it too hard and the edge chips or 2 you make it too soft and have to sharpen it a little more often but then you will have to use it quite a lot to find out either of those things.

A lot of people do long soaks at tempering, I have never seen any evidence that it doea anything. Metal is a very good conductor of heat and the structural change we want is related to heat not time, do we really think it takes 45 minutes for the inside of a 2mm piece of steel to reach the same temp as the outside? Also if it's wrapped in foil how can you see the colours and check it doesn't get too hot? I guess once you know your oven and know that it holds the right temperature then it doesn't matter but I find my fan oven has hot and cold spots and I need to keep an eye on things and be ready to take them out as soon as I see the colour I want.

 

[C_Claycomb]

There is the right way to heat treat O-1, and then there are the hundreds of ways that us folk without the right kit attempt to approximate those results.

Its for that reason than trying to use a "recipe" from someone else who doesn't have the right gear either can be a little dodgy. Their perception of colour will differ (for instance, nothing I have ever hardened has looked cherry red, dull or otherwise, at the time it has become non-magnetic, it all looks orange to me ), their quench media will differ, and the way that their tempering set up works will differ.

Best advice is to get a little bar of steel, whatever you will be working, O-1 or whatever, and do tests. Separate your hardening and tempering processes and just try things. Try cycling, multi-quench, single quench, trying to hold at temperature, and quenching immediately on a rising heat. Tempering is easier to experiment with as long as you start off by aiming low, you can always retemper something that is too hard, but if you use too much heat, and leave it a moment too long, you can't get the hardness back. By testing you will get a feel for the steel without having to wait to make a blade, or risk the grain growing through over heating or decarbing the edge in the fire, or warping or cracking on the quench.

Hillbill
I guess that the reason for foil is to prevent the blade getting hotter, through radiant heat, than the air in the oven, which is probably what the sensor measures. Have you tried it with and without foil? How did it compare? I would have thought that the variability in a forge hardening process would overshadow the effect of radiant heat in tempering A friend of mine who has an Evenheat oven, and can really control the process, uses a fish steamer full of sand to even out the tempering temperature, but he can control everything to +/- a degree or so.:Wow:

Robin
Interesting way of getting the results you want! Setting a higher temperature of 220C probably gives satisfactory results because you A) don't leave it in there long and B) keep opening the door. So the blades may never get to 220C and if they did, they would be out and cooling immediately. My oven appears to slowly ramp up in temperature so that the longer I leave things in there, the hotter they get, despite the setting on the dial. However, it takes an hour for that to happen, so I am able to leave blades for an hour to an hour ten minutes and they come out fine. My parent's oven on the other hand (its a new fangled fan assisted thing) never gets hot enough to temper anything even slightly Only after a very frustrating couple of hours was I told that they had never got it to bake bread properly either



I am the sort of person who is never entirely satisfied with my work, I am always aiming to improve and I like to get a head start on experimenting by reading up on stuff first. I found the following information by Kevin Cashen to be very interesting and useful. He has written some really good stuff on the US forums about heat treating in general, and O-1 in particular.

Info on O-1,
http://www.cashenblades.com/Info/Steel/O1.html

In tempering the end result is effected by two factors, time and temperature. Of these temperature has the most immediate and profound affect. Time at temperature has a more subtle effect, relieving stresses and increasing toughness with less loss of hardness.

http://www.cashenblades.com/Info/Tempering.html

An article on metallurgy made easy
http://swordforum.com/metallurgy/ites.html

 

[Leonidas]

Have heat treated some 01 blades in boiling brine.
Got excellent results, in fact my favourite blade was treated this way.

The beauty of using brine (as concentrated as it can be) is that it leaves the metal needing very little cleaning

Agree oil is perfect for 01 but saturated boiling brine leaves very little residue.

 

[Barney]

Seems like some crossed wires here to me. Foil and the like is used in the hardening of steels not the tempering. The generic material is Inconel foil as it is extremely resistant to oxidation and protects the steel from the environment within the high temperature oven and results in less oxidation and a reduced loss of surface carbon to atmosphere. This enables the rough grind tolerances to be a lot closer to the "finished" Size without degradation of the structure and "close to surface" steel composition.

I have tempered steel in a chip pan with a good degree of success. Many chip pans are thermostatically controlled fairly accurately up to 220 - 250, which is perfectly acceptable for the heat treatment of O1. 15 mins is fine.

 

[robin wood]

Seems like some crossed wires here to me. Foil and the like is used in the hardening of steels not the tempering. The generic material is Inconel foil as it is extremely resistant to oxidation and protects the steel from the environment within the high temperature oven and results in less oxidation and a reduced loss of surface carbon to atmosphere. This enables the rough grind tolerances to be a lot closer to the "finished" Size without degradation of the structure and "close to surface" steel composition.

I have tempered steel in a chip pan with a good degree of success. Many chip pans are thermostatically controlled fairly accurately up to 220 - 250, which is perfectly acceptable for the heat treatment of O1. 15 mins is fine.

Now I like the chip pan idea, I have a chip pan full of cold pressed linseed which should do the job nicely, defo something to try.

Chris I never pay any attention to the dial setting on any oven, the fairly cheap and cheerful oven thermometers that sit in the oven give a much lower and I suspect more truthful reading. Looking at the Cashen link you posted he has 232 c giving 60-61 rockwell and 204 giving 62-63 it obviously depends on what you are making and what hardness you want but 62-63 would be very hard too brittle for many uses. I find the colours give me a better indication of what I have achieved than any of the temperature gauges I have used. Straw is at the hard end and good for carving knives, deep straw going into bronze for tools that need more toughness or will get a battering. Whilst undoubtedly close control of all the variables and scientific method are capable of doing the job better I suspect that is the pursuit of the last 5% of function and 95% can be got easily by an amateur using simple methods. Few people actually use their tools enough to know whether they are using a 95% tool or a 100% one and rather have a tool I made myself and needs sharpening once a day than one made by someone else that can work for a week.

 

[HillBill]

The foil keeps the heat even along the length of the steel. When i temper mine they all come out an even straw colour at the times i specified. I do not open the oven to check. The first two i did i over tempered, they went blue, about 56RC a spring temper. I messed about with a machete too, getting a spring temper everywhere but the edge which i kept at 57RC using clay.

Chris i have never tried it without foil so i wouldn't know. I know what works for my setup so i keep it as is. I may try it though with an offcut of 01 at the side of a blade in foil. I'll let you know how it goes

 

[C_Claycomb]

Barney,
Since I don't have an oven, I haven't really spent all that much time thinking about high temperature foil, but what I have read about it on the US forums suggest that it isn't really good for heat treating O-1. Either you oil quench while the blade is still wrapped in its little foil packet, in which case the quench may not be fast enough, and everything is even messier, or you try to slit the packet and get the blade out before everything gets too cool. Doesn't foil come into its own more with the stainless steels that can be air quenched?

Hillbill,
Fair enough. Its hard to argue that one should try fixing something that doesn't seem to be broken! I seem to have had alright results without the foil, in fact, this is the first time I have heard of the technique. However, if it offers an advantage I thought I would at least file the info away for future reference.


Robin,
Kevin Cashen does say that those are the temperatures needed if you have soaked the O-1 at hardening temperature for enough time, 10+ minutes. If you don't soak, you don't get full hardness on quench, therefore you don't need such a high tempering temperature. This is why everyone can get away with light straw to bronze colours and get a working hardness.

As for the 5% / 95% you could be right I am just unreasonably influenced by practically all the maker's whose work, or writings, I really admire using precise control, long soaks and thermal cycles. I can't get it out of my head that they might be onto something Like I said, I like reading and am always looking to get better

 

[Barney]

Chris,

I have not done a lot of work on the metallurgy recently, but from memory the air hardening steels have a much faster snap off requirement than something like O1 which is relatively slow and therefore more conducive to an oxidation reducing atmosphere when at elevated temperatures. If I remember correctly also, most stainless has an excessive amount of free carbon within the composition. I would have to look up that though and refresh my memory regarding the carbon percentage solubility in the various compositions of the steels. one advantage of the rapidly solidified stainless steels.

PS. I dont have an oven either, I just think that I remember the theory of it. I hope that my memory is not playing tricks with me.

 

[snarble]

I have heard alot of people mentioning blowing air into forges when they are heating to harden the steel? Is this important? If so, would I get sufficient oxygen in a fire?

Thanks

Also, What is the HRC I'm aiming for?

 

[HillBill]

You need to blow air into the coals to reach the heat you need, think blacksmiths bellows. I use a hairdryer. For a knife you are lookin for HRC between 57-60, these will give you a good edge with good retention and sharpening isn't difficult.

Obviously the lower figure of 57( gransfors axes are this) will not be as hard as 59/60 but it will be easy to sharpen, whereas the opposite end will be a little more diffucult to sharpen but you won't have to sharpen it as often